Electrical connectors, outlets, switches and other wiring devices are commonly used in hazardous and non-hazardous locations. Electrical wiring devices for hazardous locations typically have enclosed housings to protect the internal components. The power supply wires are generally connected to a wire connector formed with the wiring device on a rear side of the base. The electrical wires are connected by a single screw fastener to attach the wire to the wiring device. The housing of the wiring device typically has limited internal space for the wires and the connectors that can make connecting the sires difficult in the field. The wires are often required to be wrapped or twisted around the shaft of the screw before the screw can be tightened. The limited space and construction of the housing presents difficulty in properly wrapping and twisting wire in a manner to ensure secure attachment by the screw.
Electrical connectors for use in hazardous locations are often made so that any exposed electrical components that are brought into mechanical contact with each other are not energized until after the physical contact has been completed. For this purpose, it is desirable to provide a switch, in a sealed chamber, within the connector/receptacle and to arrange the switch so that it can be closed only after the components have been joined. The switches of this form also have limited space for connecting wires and do not permit connecting more than one wire to a single connector.
While connectors for this general purpose have been devised previously, such connectors are generally complicated and expensive to produce. One example of a wiring device for use in hazardous locations is disclosed in U.S. Pat. No. 4,772,215 to Falk. This device has a housing with limited space in the open bottom end of the base to connecting wires. The device includes a single screw for each wire that requires the screw to be wrapped around the screw in the limited space of the base.
In ordinary, non-hazardous locations, it is common to provide a jumper wire from one receptacle to another so that the receptacles are on a single circuit. The receptacles constructed for non-hazardous locations often enable multiple wires to pass through the device or the openings in a mounting surface for wires without difficulty. Non-hazardous location receptacles can have a second set of terminals to connect the receptacle in series or parallel as desired.
Specialty hazardous location receptacles do not have an additional set of terminals for this purpose. The wiring devices, such as receptacles, for use in hazardous locations typically do not have space available for multiple wires and connectors. The hazardous location receptacles require either splitting, to feed downstream devices, the incoming conductors or double wiring the terminals. Splitting the incoming wires can crowd the wiring pull space in the structure or conduit. The receptacles are generally not suitable, or tested and certified for double wiring of the terminals and can increase the problems associated with loosening of the wires during use, which can lead to undesired and dangerous arcing.
While the prior devices are generally suitable for the intended purpose, there is a continuing need in the industry for improved wiring devices.